Exploring numerical simulations and impedance spectroscopic analysis of highly-efficient lead-free CH₃NH₃BiI₃-based photovoltaic

Impedance spectroscopy serves as a valuable diagnostic tool for perovskite solar cells (PSCs); however, the interpretation of data can be complicated because of the overlapping dynamic processes involved. This research offers a comprehensive methodology for the analysis of impedance spectroscopy and explores the mechanisms of charge diffusion in lead-free PSCs over a frequency spectrum ranging from 10^-2 to . The study investigates the impedance behavior of organic-inorganic PSCs with different absorber thicknesses. Thus, an investigation into () as a lead-free absorber has been conducted, employing SCAPS-1D to simulate and optimize the device structure consisting of . Cadmium sulfide (CdS) and molybdenum trioxide () serve as the electron and hole transport layers, respectively, while calcium (Ca) and iridium (Ir) act as the front and back electrodes. The optimization of absorber thickness and carrier concentration has led to a notable improvement in device performance. The analysis of temperature effects was conducted within the range of 240 to 420 K, demonstrating a decline in efficiency when exceeding ambient conditions. The optimized PSC attained a power conversion efficiency of 28.4%, a fill factor of 82.99%, an open-circuit voltage of 1.01 V, and a short-circuit current density of . This research highlights the possibility of -based lead-free PSCs as effective, stable, and sustainable alternatives for future photovoltaic technologies.